Multi-Chain Spin-Peierls Systems

Abstract

We will investigate the multi-chain and the two-dimensional spin-Peierls systems with the interchain phonon interaction. An effective spin model will be discussed where the biquadratic spin-interaction term appears by tracing out the lattice degree of freedom. Considering the scaling dimension of the interaction, the ground state of the multi-chain and the two-dimensional system will have the dimer order when the interchain interaction is unfrustrated. On the other hand, the dimer order is likely to disappear for the fully frustrated chains. The expected phase diagram of the two-dimensional spin-Peierls model will be shown; the two different-pattern dimer phases are separated by the parameter line of fully frustrated interchain interaction. The interesting phase transition will occur between the gapless spin liquid phase and the macroscopically degenerated dimer phase on the line.